This area of dry valleys, which partly overlooks the marshes, is also the home of windmills, of which Moringhem and Norbécourt still have the two finest examples. Like the windmills, the area also boasts some fine white limestone architecture: farmhouses, the churches of Saint-Léger and Saint-Gilles in Mentques with their machicolations, and Saint-Maxime in Difques with its Romanesque tower. The calvary in Nort-Leulinghem, dating from 1780 and listed as a Historic Monument, is one of the most remarkable in the region. Added to this is a fragile earthen heritage, with ancient mottes castrales that were the first castles, as in Bayenghem-les-Eperlecques and Mentques. The northern part of the region is crossed by the Hem, a river with clear, lively waters. At the ford in Zouafques, it crosses the Leulène, the ancient road leading down from England to Rome. It flows through Tournehem, an ancient medieval fortified town, with its medieval gateway, square and water mill. The river also flows through the hamlet of Guémy, where time seems to have stood still… At the top of the hill, the ancient chapel, set in a protected natural site, opens onto one of the most beautiful panoramas in northern France. The whole of the Aa delta and the Opal Coast from Calais to Dunkerque can be seen at a glance.